fix: panic when using clause.Returning with CreateInBatches (#7768)

* fix: make CreateInBatches compatible with clause.Returning by using addressable batch slice

reflectValue.Slice(i, ends).Interface() returns an unaddressable sub-slice.
When clause.Returning{} attempts to call SetLen on it via reflection during
the create callback, Go runtime panics with:
  "panic: reflect: reflect.Value.SetLen using unaddressable value"

Fix by allocating a new addressable *[]T for each batch and passing it as
Statement.Dest instead. After execution, sync the results back into the
original slice so callers receive server-generated field values (e.g.
updated_at, created_at, id) populated by RETURNING.

Reproduces when:
  - gorm.Config.CreateBatchSize > 0, OR
  - db.CreateInBatches() is called directly
  - AND clause.Returning{} is used
  - AND the database supports RETURNING (SQLite >= 3.35.0, PostgreSQL)

* add test

* fix: implement Create method to handle batch creation and prevent panic on unaddressable slice

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Co-authored-by: Khang Truong Quang <khang.tq@teko.vn>